Although an exact figure is not possible owing to questionable accuracy and destroyed records, approximately 8.5 to 10.8 million soldiers were killed during World War I. Of these deaths, 5.1 to 6.4 million were inflicted on the Allied nations, while 3.3 to 4.3 million were suffered by the Central Powers.
Of the Allied Powers, the Russian Empire suffered the greatest number of military deaths, with approximately 1.7 to 2.2 million soldiers losing their lives during the six years of war. The German Empire bore the brunt of soldier fatalities among the Central Powers, as 1.7 to 2 million were killed. Civilian deaths for the war amount to an additional 4.6 to 5.3 million people killed, making the conflict among the deadliest in human history.